Volume 7 Special Issue 1 2013
Tunisian fruit and vegetables

ISBN 978-4-907060-11-4

How to reference: Hdider C, Ilahy R, Tlili I, Lenucci MS, Dalessandro G (2013) Effect of the Stage of Maturity on the Antioxidant Content and Antioxidant Activity of High-pigment Tomato Cultivars Grown in Italy. In: Ilahy R (Ed) Tunisian Fruits and Vegetables. Food 7 (Special Issue 1), 1-7

Guest Editor

Riadh Ilahy

Université de Carthage, National Agricultural Research Institute of Tunisia, Tunisia

CONTENTS AND ABSTRACTS

Chafik Hdider, Riadh Ilahy, Imen Tlili (Tunisia), Marcello Salvatore Lenucci, Giuseppe Dalessandro (Italy) Effect of the Stage of Maturity on the Antioxidant Content and Antioxidant Activity of High-pigment Tomato Cultivars Grown in Italy (pp 1-7)

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Original Research Paper: Lycopene has attracted much interest during the last few years because of its antioxidant activity against free radicals, suggesting protective roles in reducing the risk of several chronic diseases. Therefore, tomato cultivars, with increased lycopene content have been developed. However, a detailed assessment of their nutritional value remains scarce in literature. In this study, the effect of the stage of maturity on the antioxidant content and activity of six high-lycopene tomato cultivars (‘Lyco 1’, ‘Lyco 2’, ‘HLY 02’, ‘HLY 13’, ‘HLY 18’ and ‘Kalvert’) and one ordinary (‘Donald’) was determined. The pattern of change in lycopene and β-carotene was similar in all tomato cultivars, although quantitatively higher in high-lycopene tomatoes. In those cultivars, lycopene and β-carotene were respectively 1.68- to 3.7-fold and 2.11- to 2.48-fold higher during ripening compared to ‘Donald’. The lipophilic antioxidant activity was well correlated to the lycopene and β-carotene contents. The pattern of change in total phenolic, flavonoid and total vitamin C was cultivars dependent. At the red ripe stage, ‘HLY 13’ showed the highest total vitamin C and flavonoid contents. However, ‘HLY 02’ showed the highest total phenolic content. The hydrophilic antioxidant activity was only well correlated to the phenolic and flavonoid contents.

Mehdi Trad, Wissal Dhifi, Brahim Marzouk, Messaoud Mars (Tunisia) Aroma Composition in Relation with Quality of ‘Peento’ Flat Peach during Fruit Development (pp 8-12)

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Original Research Paper: ‘Peento’ flat peach (Prunus persica L.), increasingly encountered in Tunisian agrosystems, is characterized by tasty and flavoured fruit with a marked and specific aroma that develops when ripe. Volatile compounds of ‘Peento’ peaches were separated using liquid-liquid extraction with pentane and di-ethyl ether and analysed by gas chromatography/flame ionisation detection (GC/FID). Peach samples produced an average of 3674 µg aroma/g fresh weight (FW) at full ripeness. Lactones was the major class of volatiles described with δ-dodecalactone as the main compound (18.4%) followed by δ-undecalactone (15.3%). Other constituents, including ketones (2), esters (1), alcohols (1), monoterpenes (1) and sesquiterpenes (1), were also identified. ‘Elegant Lady’ fruits, gathered during the same period, produced 2072 µg aroma/g FW. Methyl isovalerate (13.0%) and δ-undecalactone (7.9%) were the major compounds identified. δ-Dodecalactone was less abundant in the fruit aroma (3.3%) compared to flat peaches. Changes in volatile composition showed a significant increase until maturity. Besides, volatile concentrations decreased. Lactones, the greatest contributors to the peachy note, continued to rise independently of total volatiles produced. The quality of ‘Peento’ flat peach is influenced by its aroma composition, in particular to the level of lactones in the parenchyma. The date of harvest seemed to be of great importance in preserving fruit quality attributes. Physiological maturity is considered to be the optimal time for harvest. Anticipated as well delayed harvest could result in a dramatic loss of scent and aroma developed by the fruit. The emission of volatile compounds appears to be a useful index for determining the physiological maturity of ‘Peento’ peaches in an orchard prior to harvest.

Mounira Harbi, Imen Tlili, Rym Bouhlal, Sami Fattouch (Tunisia) Sugars and Total Phenolic Contents in Different Fractions of Autochthonous Grape Varieties Grown in Tunisia (pp 13-16)

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Original Research Paper: Grapes (Vitis vinifera L.) is one of the economically important fruit in the world and the important quality determining parameters of it are sweetness related compounds and antioxidants. In this experiment, reducing, sugar, total sugar and phenolic contents were quantified in different parts (peel, pulp, and seeds) of 15 grape varieties: (‘Muscat de RafRaf’, ‘Rafrafi’, ‘Boukhasla’, ‘Farrani’, ‘Bith El H'mem’, ‘Hammémi’, ‘Kohli’, ‘Chaâraoui’, ‘Vieux Beldi’, ‘Razzégui’, ‘Farranah’, ‘Bith El H'mem Rose’, ‘Essifi’, ‘Marsaoui’ and ‘Bézoul El Khadem’). Significant differences were found between grape varieties within different parts in total sugar, reducing sugar and phenolic contents. ‘Muscat de RafRaf’ variety showed the highest amount of total sugar (12.28 g 100 g^-1 FW), reducing sugar (7.43 g 100 g^-1 FW) and phenolic contents (28.33 mg EAG g^-1 FW). The pulp of grapes showed high reducing and total sugar contents. The total phenolic content varied between 0.47 and 80.93 mg EAG g^-1 FW. Seeds had a greater phenolic compound content, between 18.09 and 80.93 mg EAG g^-1 FW, which was higher than those of other fruit parts.

Imen Henan, Imen Tlili, Riadh Ilahy, Thouraya Rhim, Hager Jebari (Tunisia) Evaluation of Qualitative Parameters and Physicochemical Properties of Local Varieties of Muskmelon (Cucumis melo L.) Grown in Tunisia (pp 17-21)

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Original Research Paper: The quality characteristics, carotenoids and total phenolic contents of muskmelon cultivars (Cucumis melo L.) were investigated. Four local muskmelons varieties (‘Maazoul’, ‘Galaoui’, ‘Stambouli’, and ‘Fakkous’) were evaluated for their agronomic characteristics, total carotenoids and total phenolic contents. Significant differences were found between muskmelon varieties in carotenoid and phenolic contents. Total carotenoid content ranged from 1.15 in ‘Maazoul’ to 12.82 mg kg⁻¹ FW in ‘Galaoui’. The highest phenolic value (474.42 mg kg⁻¹ FW) was shown by ‘Galaoui’. Generally, highest content of carotenoid and total phenolics were obtained for ‘Galaoui’ variety. In fact, total carotenoid content obtained in ‘Galaoui’ was more than 12-fold higher than those obtained in ‘Maazoul’. This study demonstrates that carotenoid and total phenolic contents were greatly influenced by genotype emphasizing the need to evaluate the muskmelon biodiversity in order to improve its nutritional value.

Imen Tlili, Chafik Hdider, Riadh Ilahy, Thouraya R’him, Hager Jebari (Tunisia) Effect of Growing Period on the Agronomic Characteristics and Phenolic Content of Different Watermelon (Citrullus lanatus (Thunb.) Mansfeld) Cultivars Grown in Tunisia (pp 22-26)

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Original Research Paper: Besides some agronomic characteristics, total phenolics and flavonoid contents of different watermelon cultivars (Citrullus lanatus (Thunb.) Mansfeld), as influenced by two growing periods, were investigated. Fruits from plants grown under low plastic tunnel and open-field conditions were collected. Five watermelon cultivars (four commercial cultivars namely ‘Crimson Sweet’, ‘Dumara’, ‘Giza’, ‘Aramis’, and a new selection ‘P503’ produced by the National Agricultural Research Institute of Tunisia) were compared. The growing period significantly influenced yield, soluble solids, total phenolics and flavonoid contents of all investigated watermelon cultivars. The total phenolics in the watermelon cultivars ranged from 122.81 to 200.69 mg GAE kg⁻¹ FW in early and full seasons, respectively. The flavonoid content ranged from 150.60 to 226.44 mg RE/kg FW in early (January - May) and full (March - July) seasons, respectively. The mean total phenolics and flavonoid contents of the five cultivars was 62 and 66% higher, respectively, in full season than in early season. This study indicates that the total phenolics and flavonoid contents of watermelon can vary considerably with changes in environmental conditions.

Thouraya R’him, Riadh Ilahy, Imen Tlili, Khamassy Nouri, Jebari Hager (Tunisia) The Effect of Salinity on Some Growth and Yield Parameters of Three Pepper (Capsicum annuum L.) Varieties Grown in Tunisia (pp 27-31)

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Original Research Paper: Pepper is one of the main vegetable crops grown and consumed in Tunisia and is therefore of economic importance. Interest in the selection of salt-tolerant crop is increasing due to the decrease of water irrigation quality worldwide. Therefore, some growth and yield parameters of three pepper cultivars ‘Baker’, ‘Marconi’ and ‘Jrid’ commonly grown in Tunisia and with different pungency were determined under three different salinity levels (S1=35, S2=70 and S3= 120 mM of NaCl) with regard to a control irrigated with tap water. All the growth and yield parameters varied significantly among the studied salinity levels. No statistical differences were found in stem thickness, plant height, shoot fresh weight and root fresh weight under all the studied salinity levels and for all the studied pepper cultivars. Under (S3) salinity level, yield was decreased by 75% in ‘Jrid’, by 81% in ‘Baker’ and by 100% in ‘Marconi’. The blossom-end rot increases with increasing salinity levels in ‘Baker’ and ‘Marconi’ however no rotted fruit were observed in ‘Jrid’ under all the studied salinity levels. This study has demonstrated the variability in the responses of some pepper cultivars commonly grown in Tunisia to different salinity levels. This result can help the growers to choose such varieties in salt-rich fields or when only saline water should be used for crop irrigation. Nevertheless, there is a need to focus on the effect of these salinity levels on the nutrient, non nutrient, anti-nutrient compounds accumulation and the antioxidant activity in such cultivars.

Riadh Ilahy, Thouraya R’him, Imen Tlili, Jebari Hager (Tunisia) Effect of Different Shading Levels on Growth and Yield Parameters of a Hot Pepper (Capsicum annuum L.) Cultivar ‘Beldi’ Grown in Tunisia (pp 32-35)

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Original Research Paper: Pepper is one of the main vegetable crops grown and consumed in Tunisia and is therefore of economic importance. In Tunisia, 19400 ha were dedicated to this crop and its production amounted to 304000 t in 2010. Pepper production (crop yield and quality) in some Mediterranean regions is negatively affected by the high radiation, temperature and relative humidity particularly during spring-summer harvesting period. The use of shading screen is thought to be an efficient solution to overcome this problem and to improve pepper growth and yield. Therefore, the aim of this study was to evaluate the effect of different levels of shading on growth and yield parameters of the hot pepper (Capsicum annuum L.) cv ‘Beldi’. For this reason, two shading levels were evaluated in order to attain 50% and 100% shading which compared to open field conditions (control 0% shading). The 50% and 100% shading levels, respectively increased total plant height by 15% and 30%, internode length by 31% and 47%, leaf area by 30% and 40%, and plant yield by 5% and 24% relative to non-shaded conditions. However, 50% and 100% shading decreased the incidence of blossom end rot by 30% and 69%, respectively relative to non-shaded pepper plants. A microclimate may have been created by the shading conditions, particularly under 100% shading, during the hottest summer period (June, July and August), has improved the vegetative growth and by extending plant physiological activity.

Leila Radhouane, Sami Fattouch, Imen Tlili, Riadh Ilahy (Tunisia) Antioxidant and Polyphenol Oxidase Activity of Some Tunisian Pearl Millet (Pennisetum glaucum (L.) R.Br.) Ecotypes (pp 36-40)

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Original Research Paper: Pearl millet is a rich source of various phytochemicals, including phenolic acids. Natural compounds in food are an important health-protecting factor. In Tunisia, many autochthonous pearl millet ecotypes have generated interest because their nutritional qualities. In order to provide information on the composition of pearl millet grown under local conditions, seven ecotypes were analyzed to evaluate their nutraceutical and antioxidant properties. The nutraceutical properties were determined by evaluating the total phenolic while the antioxidant properties were studied using the DPPH free radical scavenging activity. The results showed that the total phenolic varied widely between ecotypes (from 198 to 323 mg GAE/100 g). The DPPH radical scavenging activity of all the ecotypes was relatively high. The antioxidant activity of pearl millet flour significantly varied among ecotypes and ranged from 62.5 to 86.4%. Fractionation of phenolic extracts by HPLC showed 3 major peaks and several minor peaks: Trans-cinnamic (486 to 677 µg/g of extract), protocatechic (127 to 452.4 µg/g of extract) and hydroxybenzoic (253.5 to 437.6 µg/g of extract) were the most important. Identifying ecotypes growing under local agricultural conditions with significant levels of beneficial factors could not only provide health benefit to consumers but also promote the value-added cultivation and stimulate industrial and economic growth.

Hatem Ben Mohamed, Ahlem Zrig, Habib Khemira (Tunisia) Effect of Date of Spraying CPPU (Sitofex^®) on Fruit Quality of 'Meski' Table Grapes (pp 41-43)

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Short Communication: The objective of this study was to evaluate the effect the synthetic cytokinin forchlorfenuron, most commonly known as CPPU (Sitofex^®), on fruit quality of 'Meski' table grape grown in central Tunisia. Application of 1% CPPU was performed at 1 (A), 2 (B) and 3 (C) weeks following full bloom. All treatments enhanced berry size, berry weigh and bunch weight by at least  10, 17% and 20% respectively, while bunches length improved slightly (P = 0.15). In addition, the number of berries per bunch was increased only by treatments A and B. Yet, these two treatments significantly increased fruit set which produced very compacted and unmarketable bunches. On the other hand, CPPU application reduced °Brix and pH of bunches juice and then delayed maturity which can be advantageous in fresh market fruit. In conclusion, the best results with regard to fruit size and quality of 'Meski' table grape were obtained when CPPU was sprayed at 1% (v/v) three weeks after full bloom. However, early applications will be more advantageous if combined with a growth regulator that allowed better growth of the rachis.

Chafik Hdider, Riadh Ilahy, Imen Tlili, Nasr Abdelaali (Tunisia) Agronomic Characteristics and Physicochemical Properties of Selected Citrus Cultivars Grown in Tunisia (pp 44-46)

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Short Communication: Citrus is a popular horticultural crop. Interest in assessing agronomic and bioactive compounds with antioxidant capacity and potential health benefits in Citrus is increasing. Besides some agronomic characteristics, the variability in total carotenoids and lycopene contents of ten Citrus cultivars (five oranges including the pigmented cultivars ‘Moro’, ‘Tarocco’, ‘Sakasli’, and ‘Maltaise’, ‘Demi Sanguine’ and the blond cultivar ‘Maltaise Blonde’; two mandarins ‘Fortune’ and ‘Minneola’; one citron ‘Marsh’; one pomelo ‘Star Ruby’; and one Clementine ‘Hernandina’ were investigated. The results showed significant differences in total carotenoids and lycopene contents between Citrus cultivars. Total carotenoid content ranged from 5.33 mg/kg FW in ‘Hernandina’ to 23.66 mg/kg FW in ‘Star Ruby’. Lycopene content ranged from 0.27 mg/kg FW in ‘Maltaise Blonde’ to 17.93 mg/kg FW in ‘Star Ruby’. Therefore, the highest total carotenoids and lycopene values were shown by the pomelo ‘Star Ruby’. This study demonstrates that the amount of total carotenoid and lycopene was influenced by genotype, emphasizing the need to evaluate Citrus biodiversity in order to improve its nutritional value and to contribute towards increasing the intake of antioxidants.